In buggy summer conditions, I'll always take a single-walled tent and no amount of persuasion can convince me that a few extra ounces isn't worth it.
However, I'm gearing up for an August solo modified-JMT trip. I'll be going out of Yosemite over Isberg pass, then a bit of xc from Hemlock Crossing > Twin Island Lakes > Lake Catherine > Thousand Island Lakes. Once on JMT I'll be taking side trips and camping often in higher spots (not the highest peaks but possibly exposed ridges) for twilight/night photography. I have experience in high Sierra but not camping in exposed places (it always seemed more logical to seek out lower/sheltered locations).
In an earlier life in the 90s I used to cowboy camp a lot in the Sierra. And by that I mean nothing but sleeping bag (synthetic) and groundsheet. If weather looked scary in the evening, I would find good shelter and set up my tarp, which was a blue thing purchased from from AutoMart for all I know. I have no experience yet with a proper UL tarp/bivy or bathtub floor, nor cowboy camping with a down sleeping bag.
As of the last 15 minutes, I'm leaning toward ZPacks Hexamid Solo Tarp (5.8 oz. w/ "beak" and lines) plus bathtub groundsheet (3.5 oz. including elastic attachment bands). I know from reading around here that this might be considered on the *minimal* side for weather protection. I'm trying to calibrate that against my needs for middle August and some (but not extreme) exposure. Again, I'm may be up high but I don't particularly like being exposed and I'm going to look for the best protection provided by local terrain or go lower if weather is obviously brewing.
How much safety margin does a bivy provide over a (pretty good) bathtub floor for rough weather? How much better/worse is a bivy for managing condensation on a calm but cold high Sierra night? From cowboy camping without a bivy, I'm used to having dew condensation on the surface of my sleeping bag that never seemed to soak through and quickly dried out in the morning (that's wearing all my cloths while using my old 35F synthetic; I now own a 20F ZPacks down bag plus down hood). Some bivy users describe having damp feet often (eg, sectionhiker) although in very different conditions than where I will be. I am persuadable though. I'll carry the extra ~3 oz. and pay the extra ~$hundred plus if I think a bivy provides enough extra benefit. Does it?
I've also read but not researched much about alternative tarps that may be more weather worthy. MLD Patrol for example. I believe it is always assumed that this is paired with a bivy. It's a tiny bit heavier and less roomy (but I'm 5'8" and don't need much room). So the question: Is the Hexamid Solo w/ beak up to the task for somewhat (but not extreme) exposed high Sierra camping? Or should weather safety motivate me to look at alternatives?
